1. Cross Reference to Related Applications
The present application is related to the pending application of John L. Baugh, et al, Ser. No. 06/876,515, filed June 20, 1986, entitled "SLIP GRIPPING MECHANISM", now U.S. Pat. No. 4,711,326, to the pending application of Sidney Kenneth Smith, Jr., et al, Ser. No. 943,531, filed Dec. 18, 1986, entitled "MECHANICALLY ACTUATED SLIP GRIPPING MECHANISM", and to the pending application of Sidney Kenneth Smith, Jr., Ser. No. 077,559, entitled "SLIP GRIPPING MECHANISM WITH FLOATING CONE SEGMENTS" filed concurrently herewith.
2. Field of the Invention
This invention relates to improvements in well tools of the type having slip assemblies for grippingly engaging surrounding cylindrical conduits.
3. Description of the Prior Art
Slip assemblies for well packers and liner hangers are actuated in order to support a conduit within the cased bore of a well. Prior art slip gripping mechanisms have generally included a plurality of wedge-shaped slip elements carried in circumferentially spaced-apart relation about a generally conically shaped expander surface on the tool body. More particularly, the lower surface portions of the slips are slidable over complimentary surfaces on the expander so as to cause teeth on the upper surfaces of the slips to be moved between expanded and contracted positions in response to relative axial movement of the slip elements and expander. This relative movement can be induced hydraulically or by mechanical actuation of telescopingly arranged, axially reciprocal members of the tool to which the slips and expanders are connected.
One disadvantage in the prior art gripping mechanisms lies in the fact that the loading imposed by the cylindrical conduit is transmitted radially from the expanders to the slips and radially into the surrounding well casing. At times, the loading can cause the casing to burst.
Prior arts slip gripping mechanisms have generally formed a part of a special hanger body or sub which included an internal mandrel that required consideration in determining the maximum support load of the tool. The hanger body was usually manufactured from special high strength material which differed from the material of the remainder of the cylindrical conduit being supported in the well bore.
The present invention has as its object the provision of a slip gripping mechanism for supporting a string of conduit within the interior bore of a circumscribing conduit which distributes the load being supported in a circumferential direction, rather than imposing a radial load.
Another object of the invention is the provision of a slip gripping mechanism which can be received upon the exterior surface of a standard string of cylindrical conduit and which does not require the presence of a special sub or hanger body within the string.
Another object of the invention is the provision of a unique slip and cone gripping arrangement which includes floating cone segments that allow the metal of the gripping mechanism to flex more equally, thereby reducing stress build-up during high load applications and consequently reducing the chance of permanent deformation of the slip and cone components of the mechanism.
Another object of the invention is the provision of an attachment device for fixing the cones against axial movement with respect to the cylindrical conduit without imposing radial loading upon the cylindrical conduit during use.
Additional objects, features and advantages will be apparent in the written description which follows.